[jQuery] :not selector ---> not working

[jQuery] :not selector ---> not working


Hi,
I tried a eg for :not operator.According to which it should not pick
up the Table header but it does .what am i missing.
One more question ....
what is the significance of putting the 'th' in the square bracket .is
it OK to write like this.
$('tr:not(th):even').addClass('even');
THnks
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html;
charset=utf-8" />
<title>New Web Project</title>
<style type='text/css'>
.even{
background-color:blue;
}
</style>
<script type="text/javascript" src="/lib/jquery/
jquery.js"></script>
<script type="text/javascript">
$(document).ready(function(){
$('tr:not([th]):even').addClass('even');
})
</script>
</head>
<body>
<table>
<tr> <th>Title</th> <th>Category</th> </tr>
<tr> <td>As You Like It</td> <td>Comedy</td></tr>
<tr> <td>All's Well that Ends Well</td> <td>Comedy</td></tr>
<tr> <td>Hamlet</td> <td>Tragedy</td></tr>
<tr> <td>Macbeth</td> <td>Tragedy</td></tr>
<tr> <td>Romeo and Juliet</td> <td>Tragedy</td></tr>
<tr> <td>Henry IV, Part I</td> <td>History</td></tr>
<tr> <td>Henry V</td> <td>History</td></tr>
</table>
</body>
</html>